Process for the removal of haloalkyne impurities from (hydro)halocarbon compositions

ABSTRACT

The invention relates to a process comprising contacting a composition comprising a (hydro)halocarbon and a compound of formula R f —C═CX with a basic solution comprising an hydroxide, an alkoxide and/or an amide to reduce the concentration of R f —C═CX, wherein R f  is a perfluorinated alkyl group and X is H, F, Cl, Br, or I. The invention further relates to process for preparing a (hydro)halocarbon comprising (i) converting a starting material, optionally in the presence of HF and/or a catalyst, to a composition comprising the (hydro)halocarbon and a compound of formula R f —C≡CX, wherein R f  is a perfluorinated alkyl group and X is H, F, Cl, Br, or I; (ii) contacting the composition with a basic solution comprising an hydroxide, an alkoxide and/or an amide to reduce the concentration of the compound of formula R f —C≡CX; and (iii) recovering the (hydro)halocarbon.

The present invention relates to processes for reducing theconcentration of compounds of formula R_(f)—C≡CX in a compositioncomprising at least one (hydro)halocarbon.

The listing or discussion of a prior-published document in thisspecification should not necessarily be taken as an acknowledgement thatthe document is part of the state of the art or is common generalknowledge.

(Hydro)halocarbons are typically used as refrigerant or propellantmaterials and as blowing agents. Over the last 20 years the variety of(hydro)halocarbons used in these applications has changed as it has beendiscovered that some such materials (e.g. difluorodichloromethane,CFC-12) deplete the earth's ozone layer, while others (e.g.1,1,1,2-tetrafluoroethane, HFC-134a) have an unacceptably high action asa greenhouse gas.

Hydro(chloro)fluoroolefins have emerged as a class of compounds whichmay address these problems by providing good performance asrefrigerants, propellant materials and/or as blowing agents, while alsohaving a low ozone depletion potential and a low global warmingpotential.

For example, (hydro)fluoroalkenes, such as 2,3,3,3-tetrafluoropropene(HFO-1234yf), are increasingly being considered as working fluids inapplications such as refrigeration, heat pumping, foam blowing, fireextinguishers/retardants, propellants and solvency (e.g. plasma cleaningand etching). However, the processes used to make (hydro)fluoroalkenescan lead to the generation of toxic and/or otherwise undesirableby-products.

At the elevated temperatures (e.g. in excess of 300° C.) typicallyconsidered to be necessary to achieve commercially desirable rates ofreaction in the preparation of hydro(chloro)fluoroolefins, many sidereactions become possible, including dehydrohalogenations,hydrohalogenations and rearrangements. Thus, the crude product mixtureexiting the reaction train can contain many species other than the feedsand desired product.

For example, HFO-1234yf can be dehydrofluorinated under the reactionsconditions in which it is prepared to yield 3,3,3-trifluoropropyne(trifluoromethylacetylene, TFMA). Although by-products such as TFMA mayonly be formed in small quantities relative to the desired product (e.g.HFO-1234yf), the presence of such by-products in HFO-1234yf compositionscan impair its toxicity, stability (chemical/oxidative) and/orcompatibility with refrigeration system components such as hoses orlubricants. Some applications therefore require very low levels ofimpurities. Unfortunately, some of the species formed have very similarphysical properties to the desired (hydro)halocarbon compounds orassociate with them, making normal separation methods, such asdistillation or phase separation, ineffective.

Thus, there is a need for new methods for removing reaction by-productsfrom (hydro)halocarbon compounds.

In a first aspect of the invention, there is provided a processcomprising contacting a composition comprising a (hydro)halocarbon and acompound of formula R_(f)—C≡CX with a basic solution comprising anhydroxide, an alkoxide and/or an amide to reduce the concentration ofR_(f)—C≡CX, wherein R_(f) is a perfluorinated alkyl group and X is H, F,Cl, Br, or I.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of “a” or “an” are employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. In case of conflict, thepresent specification, including definitions, will be taken. Althoughmethods and materials similar or equivalent to those described hereincan be used in the practice or testing of embodiments of the presentinvention, suitable methods and materials are described below. Inaddition, the materials, methods, and examples are illustrative only andnot intended to be limiting.

When an amount, concentration, or other value or parameter is given aseither a range, preferred range or a list of upper preferable valuesand/or lower preferable values, this is to be understood as specificallydisclosing all ranges formed from any pair of any upper range limit orpreferred value and any lower range limit or preferred value, regardlessof whether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. All percentage values are by weight unless otherwisespecified.

The term ‘(hydro)halocarbon’ refers to any saturated or unsaturatedhydrocarbon where at least one hydrogen atom (and optionally allhydrogen atoms) are replaced by a fluorine, chlorine, bromine and/oriodine atom. In a preferred embodiment, the (hydro)halocarbon isunsaturated. For the avoidance of doubt, the composition comprising a(hydro)halocarbon (and a compound of formula R_(f)—C≡CX) can contain asingle (hydro)halocarbon compound or a plurality of such compounds.

In a preferred embodiment, the (hydro)halocarbon is an hydrofluoroolefin(HFO). Preferably, the (hydro)halocarbon is a C₃₋₇ (hydro)haloalkene,such as a C₃₋₄ hydrohaloalkene. Examples of C₃₋₄ hydrohaloalkenesinclude hydrofluoropropenes, hydrochlorofluoropropenes,hydrofluorobutenes, hydrochlorofluorobutenes and (hydro)fluoropropenes.Advantageously, the (hydro)halocarbon is a hydrohalopropene.

In one embodiment, the hydrohalopropene is tetrafluoropropene and/or achlorotrifluoropropene. Preferred tetrafluoropropenes are2,3,3,3-tetrafluoropropene (CF₃CF═CH₂, HFO-1234yf) and/or E, Z orE/Z-1,3,3,3-tetrafluoropropene (CF₃CH═CHF, HFO-1234ze). Preferredchlorotrifluoropropenes are E, Z or E/Z-1-chloro-3,3,3-trifluoropropene(CF₃CH═CHCl, HCFO-1233zd) and/or 2-chloro-3,3,3-trifluoropropene(CF₃CCl═CH₂, HCFO-1233xf).

HFO-1234ze may exist as one of two configurational isomers, E or Z.HFO-1234ze as used herein refers to the isomers, E-HFO-1234ze orZ-HFO-1234ze, as well as any combinations or mixtures of such isomers.

HCFO-1233zd also may exist as one of two configurational isomers, E orZ. HCFO-1233zd as used herein refers to the isomers, E-HCFO-1233zd orZ-HCFO-1233zd, as well as any combinations or mixtures of such isomers.

R_(f) in the compound of formula R_(f)—C≡CX typically is C₁₋₅perfluorinated alkyl group, preferably a C₁-2 perfluorinated alkyl groupsuch as a perfluorinated methyl group. In one embodiment, X═H, F or Cl,preferably H and Cl. Preferred compounds of formula R_(f)—C≡CX are1-chloro-3,3,3-trifluoropropyne (CF₃C≡CCl) and 3,3,3-trifluoropropyne(CF₃C≡CCl, trifluoromethylacetylene, TFMA).

It is known that alkynes such as TFMA can be produced by thedehydrohalogenation of hydrohaloalkenes by bases. See, for example,pages 1530 to 1532 of ‘March's Advanced Organic Chemistry’ 6^(th)Edition and EP-A-2143702. On the basis of such teaching, one mightexpect that contacting a composition comprising a (hydro)halocarbon anda compound of formula R_(f)—C≡CX with a basic solution comprising anhydroxide, alkoxide and/or amide would, if anything, increase theconcentration of R_(f)—C≡CX. However, it has surprisingly been foundthat the use of a basic solution comprising an hydroxide, alkoxideand/or amide can effectively remove at least a portion of compounds offormula R_(f)—C≡CX from compositions as described above.

For the avoidance of doubt, it should be understood that the contactingstep of the present invention is distinct from any earlier steps thatmay have been taken to prepare the (hydro)halocarbon. For example, thepreparation of a C₃₋₇ (hydro)fluoroalkene by dehydrohalogenation of acorresponding C₃₋₇ hydro(halo)fluoroalkene using a basic solutioncomprising an hydroxide is known. See, for instance, WO 2008/075017. Thecontacting step of the process of the present invention is separate fromany reaction step in which the C₃₋₇ (hydro)fluoroalkene (or other(hydro)halocarbon) is formed (such as described in WO 2008/075017),irrespective of whether any compound of formula R_(f)—C≡CX is alsoformed in such a reaction step.

A basic solution comprising an hydroxide, alkoxide and/or amide is usedto reduce the concentration of R_(f)—C≡CX in the process of theinvention. Preferably, the base is one or more of an alkali metalhydroxide, alkoxide or amide, an alkaline earth metal hydroxide,alkoxide or amide, NR₄OH, wherein R is, independently, H, C₁₋₁₀ alkyl,aryl (e.g. phenyl, naphthyl or pyridinyl) or arylalkyl group (e.g.benzyl or C₁₋₁₀ alkyl-substituted phenyl).

Advantageously, the base is selected from potassium hydroxide (KOH),sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)₂), ammonium hydroxide(NH₄OH), potassium methoxide, sodium methoxide, potassium ethoxide,sodium ethoxide and sodium amide (NaNH₂). In a preferred embodiment, thebase is sodium ethoxide, KOH, NaOH or Ca(OH)₂. Preferably, the base isKOH, NaOH or Ca(OH)₂. KOH and NaOH currently are most preferred.

The basic solution comprising an hydroxide, alkoxide and/or amide usedin the contacting step of the invention typically has a concentration offrom about 0.1 to about 10 M, preferably from about 0.2 to about 5 M,such as from about 0.5 to about 3 M, from about 0.5 to about 2 M, orfrom about 0.6 to about 2 M. Without being bound by theory, it isbelieved that the identified concentrations of are high enough forreaction with/removal of the compound of formula R_(f)—C≡CX and lowenough so as not to react with the (hydro)halocarbon (e.g. to producefurther R_(f)—C≡CX).

Further to this, a lower concentration of the basic solution is believedto have the advantage of reducing the likelihood of precipitation of anycorresponding fluoride salts (e.g. NaF, KF, etc.).

Typically, the solvent for the basic solution comprising an hydroxide,alkoxide and/or an amide used in the contacting step is selected fromwater (i.e. an aqueous solution), alcohols (e.g. methanol, ethanol andn-propanol and i-propanol), diols, polyols (e.g. polyalkylene glycolssuch as PEG300), polar aprotic solvents (e.g. diglyme and N-methylpyrrolidone), ethers and cyclic ethers (e.g. diethyl ether, dibutylether, tetrahydrofuran), esters (e.g. methyl acetate, ethyl acetate,etc.), linear, branched and cyclic alkanes (e.g. cyclohexane,methylcyclohexane), fluorinated derivatives thereof (e.g.hexafluoroisopropanol, perfluorotetrahydrofuran) and mixtures of theforegoing. In a preferred embodiment, the solvent is selected fromwater, alcohols and mixtures thereof. The currently preferred solvent iswater, alone or in combination with any of the foregoing as aco-solvent.

The contacting step of the invention typically is carried out at atemperature of from about 0 to about 100° C., such as from about 10 toabout 80° C., preferably from about 20 to about 60° C. The process maybe carried out at subatmospheric, atmospheric or superatmosphericpressure, preferably atmospheric or superatmospheric pressure. Suitablepressures include from 0 bar to about 30 bar, such as from about 0.5 barto about 20 bar, preferably from about 1 to about 5 or about 10 bar.

The composition typically is contacted with the basic solutioncomprising an hydroxide, alkoxide and/or amide for from about 1 secondto about 4 hours, preferably from about 10 seconds to about 3 hours,such as from about 1 minute to about 180 minutes, preferably from about2 to about 100 minutes, from about 5 to about 80 or from about 10 toabout 60 minutes (e.g. from about 15 to about 45 minutes). Thisso-called residence time, together with other variables such astemperature of the contacting step and concentration of the basicsolution comprising an hydroxide, alkoxide and/or amide, have beendemonstrated (see later in the specification) to be important parametersin the process of the invention.

The composition comprising the (hydro)halocarbon and a compound offormula R_(f)—C≡CX can be in the liquid phase or in the gas phase(preferably the gas phase) when contacted with the basic solutioncomprising an hydroxide, alkoxide and/or amide.

Prior to contacting the basic solution comprising an hydroxide, alkoxideand/or amide, the composition preferably comprises at least about 90% byweight of the (hydro)halocarbon, such as at least about 95%, 98%, 99% or99.5% by weight of the (hydro)halocarbon.

Prior to contacting the basic solution comprising an hydroxide and/oramide, the composition typically comprises about 10000 ppm or less ofthe compound of formula R_(f)—C≡CX, such as 5000 ppm or less.Preferably, the composition comprises less than about 4000 ppm, 3000ppm, 2000 ppm, 1000 ppm, 800 ppm, 700 ppm, 600 ppm or 500 ppm or less ofthe compound of formula R_(f)—C≡CX prior to contacting the basicsolution comprising an hydroxide, alkoxide and/or an amide.

The amount of the compound of formula R_(f)—C≡CX in the(hydro)halocarbon-containing composition is reduced in the process ofthe invention, typically by at least about 20% by weight of thecomposition, preferably by at least about 50%, 60%, 70%, 80%, 90% or 95%or more by weight of the composition.

Following contacting the basic solution comprising an hydroxide,alkoxide and/or amide, the composition typically comprises from 0 toabout 1000 ppm of the compound of formula R_(f)—C≡CX, such as from 0 toabout 500 ppm. Preferably, the composition comprises less than about 400ppm, 300 ppm, 200 ppm, 100 ppm, 50 ppm, 40 ppm, 30 ppm, 20 ppm, 10 ppmor 5 ppm or less of the compound of formula R_(f)—C≡CX followingcontacting the basic solution comprising an hydroxide, alkoxide and/oran amide.

In one embodiment, the contacting step is carried out in the presence ofa phase transfer catalyst. The term “phase transfer catalyst”, as usedherein, means a substance that facilitates the migration of a chemicalcompound from one phase into another phase. The phase transfer catalystcan be ionic or neutral and is typically selected from the groupconsisting of crown ethers, onium salts, cryptands and polyalkyleneglycols and derivatives thereof (e.g. fluorinated derivatives thereof).

Typically, the amount of catalyst used is from about 0.001 to about 20wt % by weight of the composition, such as from about 0.01 to about 10wt %, for example from about 0.5 to about 5 wt %.

Crown ethers are cyclic molecules in which ether groups are connected bydimethylene linkages. Useful crown ethers include 18-crown-6, 15-crown-5and 12-crown-4. Derivatives of the above crown ethers are also useful,such as dibenzyl-18-crown-6, dicyclohexanyl-18-crown-6,dibenzyl-24-crown-8 and dibenzyl-12-crown-4. Other compounds analogousto the crown ethers and useful for the same purpose are compounds whichdiffer by the replacement of one or more of the oxygen atoms by otherkinds of donor atoms, particularly N or S. Fluorinated derivatives ofall the above may also be used.

Cryptands are another class of compounds useful in the base-mediateddehydrohalogenation as phase transfer catalysts. These are threedimensional polymacrocyclic chelating agents that are formed by joiningbridgehead structures with chains that contain properly spaced donoratoms. The donor atoms of the bridges may all be O, N, or S, or thecompounds may be mixed donor macrocycles in which the bridge strandscontain combinations of such donor atoms. Suitable cryptands includebicyclic molecules that result from joining nitrogen bridgeheads withchains of (—OCH₂CH₂—) groups, for example as in [2.2.2]cryptand(4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, availableunder the brand names Kryptand 222 and Kryptofix 222).

Onium salts that may be used as catalysts in the base-mediateddehydrohalogenation process include quaternary phosphonium salts andquaternary ammonium salts, which may be represented by the formulaeR¹R²R³R⁴P⁺Z⁻ and R¹R²R³R⁴N⁺Z⁻, respectively. In these formulae, each ofR¹, R², R³ and R⁴ typically represent, independently, a C₁₋₁₀ alkylgroup, an aryl group (e.g. phenyl, naphthyl or pyridinyl) or anarylalkyl group (e.g. benzyl or C₁₋₁₀ alkyl-substituted phenyl), and Z⁻is a halide or other suitable counterion (e.g. hydrogen sulphate).

Specific examples of such phosphonium salts and quaternary ammoniumsalts include tetramethylammonium chloride, tetramethylammonium bromide,benzyltriethylammonium chloride, methyltrioctylammonium chloride(available commercially under the brands Aliquat 336 and Adogen 464),tetra-n-butylammonium chloride, tetra-n-butylammonium bromide,tetra-n-butylammonium hydrogen sulphate, tetra-n-butylphosphoniumchloride, tetraphenylphosphonium bromide, tetraphenylphosphoniumchloride, triphenylmethylphosphonium bromide andtriphenylmethylphosphonium chloride. Benzyltriethylammonium chloride ispreferred for use under strongly basic conditions. Quaternary ammoniumchloride salts are a preferred class of onium salts for use as phasetransfer catalysts, for example Aliquat 336.

Other useful onium salts include those exhibiting high temperaturestabilities (e.g. up to about 200° C.), for example4-dialkylaminopyridinium salts, tetraphenylarsonium chloride,bis[tris(dimethylamino)phosphine]iminium chloride andtetrakis[tris(dimethylamino)phosphinimino]phosphonium chloride.

Polyalkylene glycol compounds useful as phase transfer catalysts may berepresented by the formula R⁶O(R⁵O)_(m)R⁷ wherein R⁵ is a C₁₋₁₀ alkylenegroup, each of R⁶ and R⁷ are, independently H, a C₁₋₁₀ alkyl group, anaryl group (e.g. phenyl, naphthyl or pyridinyl) or an arylalkyl group(e.g. benzyl or C₁₋₁₀ alkyl-substituted phenyl), and m is an integer ofat least 2. Preferably, both R⁶ and R⁷ are the same, for example theymay both be H.

Such polyalkylene glycols include diethylene glycol, triethylene glycol,tetraethylene glycol, pentaethylene glycol, hexaethylene glycol,diisopropylene glycol, dipropylene glycol, tripropylene glycol,tetrapropylene glycol and tetramethylene glycol, monoalkyl glycol etherssuch as monomethyl, monoethyl, monopropyl and monobutyl ethers of suchglycols, dialkyl ethers such as tetraethylene glycol dimethyl ether andpentaethylene glycol dimethyl ether, phenyl ethers, benzyl ethers ofsuch glycols, and polyalkylene glycols such as polyethylene glycol(average molecular weight about 300) and polyethylene glycol (averagemolecular weight about 400) and the dialkyl (e.g. dimethyl, dipropyl,dibutyl) ethers of such polyalkylene glycols.

Combinations of phase transfer catalysts from within one of the groupsdescribed above may also be useful as well as combinations or mixturesfrom more than one group.

In one embodiment, the composition comprising a (hydro)halocarbon and acompound of formula R_(f)—C≡CX may be a product stream from a processfor producing the (hydro)halocarbon. Accordingly, the compositiontypically contains a target or desired (hydro)halocarbon, such as ahydrohalopropene (for instance a tetrafluoropropene, e.g. HFO-1234yf orHFO-1234ze, and/or a chlorotrifluoropropene, e.g. HCFO-1233zd orHCFO-1233xf) and one or more (undesired) (hydro)halocarbon by-products.The process can be conducted as a batch reaction, a continuous reactionor as a semi-continuous reaction.

Examples of such (hydro)halocarbon by-products, for instance inprocesses for producing tetrafluoropropenes (e.g. HFO-1234yf) and/orchlorotrifluoropropene (e.g. HCFO-1233xf), include pentafluoropropenes(e.g. CF₃CFH═CFH, HFO-1225ye), pentafluoropropanes (e.g. HFC-245eband/or HFC-245fa and/or HFC-245cb), chlorotetrafluoropropanes (e.g.HCFC-244bb) and hexafluoropropanes (e.g. CF₃CFHCF₂H, HFC-236ea).

Unexpectedly, it has been found that the contacting step of theinvention is effective at reducing the concentration of not only thecompound of formula R_(f)—C≡CX, but it can also be effective at reducingthe concentration of one or more by-products present in a compositioncontaining the target (hydro)halocarbon, compound of formula R_(f)—C≡CXand (hydro)halocarbon by-product. This results in an increase inselectivity and/or yield for the desired (hydro)halocarbon. Preferably,the concentration of any saturated (hydro)halocarbon by-products isreduced relative to the desired (hydro)halocarbon.

The amount of (hydro)halocarbon by-product in the desired(hydro)halocarbon-containing composition typically is reduced in theprocess of the invention by at least about 20% by weight of thecomposition, preferably by at least about 50%, 60%, 70%, 80%, 90% or 95%or more by weight of the composition.

Following contacting the basic solution comprising an hydroxide,alkoxide and/or amide, the composition typically comprises from 0 toabout 1000 ppm of the compound of the (hydro)halocarbon by-product, suchas from 0 to about 500 ppm. Preferably, the composition comprises lessthan about 400 ppm, 300 ppm, 200 ppm, 100 ppm, 50 ppm, 40 ppm, 30 ppm,20 ppm, 10 ppm or 5 ppm or less of the (hydro)halocarbon by-productfollowing contacting the basic solution comprising an hydroxide,alkoxide and/or amide.

In a second aspect of the invention, there is provided a process forpreparing a (hydro)halocarbon comprising:

-   -   (i) converting a starting material, optionally in the presence        of HF and/or a catalyst, to a composition comprising the        (hydro)halocarbon and a compound of formula R_(f)—C≡CX, wherein        R_(f) is a perfluorinated alkyl group and X is H, F, Cl, Br, or        I;    -   (ii) contacting the composition with a basic solution comprising        an hydroxide, an alkoxide and/or an amide to reduce the        concentration of the compound of formula R_(f)—C≡CX; and    -   (iii) recovering the (hydro)halocarbon.

For the avoidance of doubt, the information described above inconnection with the first aspect invention, for example regarding thecomposition comprising a (hydro)halocarbon and a compound of formulaR_(f)—C≡CX and the contacting step, is also applicable to the secondaspect of the invention. Further embodiments of the second aspect of theinvention are described hereinafter.

The conversion of the starting material to the (hydro)halocarbon andR_(f)—C≡CX impurity in step (i) preferably comprises an hydrogenationreaction, a dehydrohalogenation reaction, an isomerisation reactionand/or a fluorination reaction.

In an embodiment, the composition comprising the (hydro)halocarbon and acompound of formula R_(f)—C≡CX is prepared by an hydrogenation reaction.

Such hydrogenation reaction(s) may be carried out in the liquid orvapour phase, preferably the vapour phase, typically at a temperature offrom about −50 to about 275° C. Preferred temperatures for liquid phasehydrogenation are from about −50 to about 50° C., e.g. from about 15 toabout 40° C. Preferred temperatures for vapour phase hydrogenation arefrom about 0 to about 250° C., such as from about 20 to about 200° C.,e.g. from about 50 to about 150° C.

The hydrogenation reaction(s) may be carried out in the presence of afluorinated polar aprotic solvent, particularly when carried out in theliquid phase. Suitable solvents include HFCs (e.g. 134a) and PFCs (e.g.perfluorodecalin).

The hydrogenation reaction(s) may be carried out at atmospheric, sub- orsuper-atmospheric pressure, preferably super-atmospheric pressure. Forexample, the hydrogenation may be carried out at a pressure of fromabout 0 to about 40 bara, such as from about 1 to about 30 bara, e.g.from about 5 to about 20 bara.

The ratio of hydrogen:reagents is suitably from about 0.1:1 to about40:1, such as from about 1:1 to about 20:1, preferably, from about 1.1:1to about 10:1, e.g. from 1.5:1 to about 5:1.

The hydrogenation reaction(s) typically are carried out in the presenceof a catalyst. Suitable hydrogenation catalysts include those comprisingthe transition metals nickel (Ni), palladium (Pd), platinum (Pt),rhenium (Re), rhodium (Rh), ruthenium (Ru) and mixtures thereof. Suchcatalysts may be supported on, for example, alumina, titania, silica,zirconia, fluorides of the foregoing, calcium fluoride, carbon or bariumsulphate, or they may be unsupported, for example Raney Ni or Pd metalproduced by reduction of PdO₂. Examples of catalysts suitable for use inthe present invention include Pd/alumina, Pd/barium sulphate, Pd/C andchlorotris(triphenylphosphine)rhodium(I). Preferably, the catalyst ispalladium supported on carbon (Pd/C) orchlorotris(triphenylphosphine)rhodium(I) (Wilkinson's catalyst) orplatinum supported on alumina (Pt/Al₂O₃) or Adams catalyst, PtO₂,reduced in situ to platinum metal. When Pd/C is used as the catalyst,the Pd is present in an amount of from about 0.01 to about 10% by weightof the catalyst, such as from about 0.1 to about 5%

The hydrogenation catalyst typically is used in an amount of from about0.01 to about 30% by weight based on the total weight of the componentswhich make up steps (a) and (c), such as from about 0.1 to about 10%.When Pd/C is used as the catalyst, the Pd is present in an amount offrom about 0.01 to about 10% by weight of the catalyst, such as fromabout 0.1 to about 5%.

In the vapour phase the contact time for the catalyst may be from about1 to about 200 seconds, such as from about 2 to about 150 seconds. Inthe liquid phase the contact time for the catalyst with suitably is fromabout 1 to about 180 minutes, such as from about 2 to about 60 minutes.

In an embodiment, the composition comprising the (hydro)halocarbon and acompound of formula R_(f)—C≡CX is prepared by a dehydrohalogenationreaction.

The dehydrohalogenation reaction may be carried out by pyrolysing thestarting material to produce the composition comprising the(hydro)halocarbon and a compound of formula R_(f)—C≡CX. By the term“pyrolysing” or “pyrolysis”, as used herein, we include the meaning ofchemical change produced by heating in the absence of catalyst. Byabsence of catalyst, we include the meaning that no material ortreatment is added to the pyrolysis reactor that increases the reactionrate by reducing the activation energy of the pyrolysis process.

Any suitable reactor can be used for the pyrolysis, for example acylindrical tube, either straight or coiled. Preferred pyrolysisreactors include those in which the flow of gases through the reactor ispartially obstructed to cause back-mixing, i.e. turbulence, and therebypromote mixing of gases and good heat transfer. This partial obstructioncan be conveniently obtained by placing packing within the interior ofthe reactor, filling its cross-section or by using perforated baffles.The reactor packing can be particulate or fibrillar, has an openstructure like that of Raschig Rings or other packings with a high freevolume to avoid the accumulation of coke and to minimize pressure drop,and permits a generally free flow of gas. In some embodiments of thisinvention, the reactor packing is in cartridge disposition for ease ofinsertion and removal. In some embodiments of this invention, thepyrolysis reactor is substantially empty which means that the freevolume of the reaction zone (the volume of the reaction zone minus thevolume of the material that makes up the reactor packing) is at leastabout 80%, preferably at least about 90% and more preferably at leastabout 95%. In some embodiments, the pyrolysis reactor is comprised ofmaterials which are resistant to corrosion including stainless steel,Hastelloy®, Inconel®, Monel®, gold, or gold-lined or quartz.

The dehydrohalogenation reaction of step (i) preferably comprisesdehydrofluorination process and/or dehydrochlorination depending on thestarting material and the corresponding (hydro)halocarbon product. Thepyrolysis temperature for dehydrofluorination typically is higher thanfor dehydrochlorination. For example, dehydrofluorinating pyrolysis maybe conducted at a temperature of from about 600° C. to about 900° C. anddehydrochlorinating pyrolysis may be conducted at a temperature of fromabout 400° C. to about 700° C.

In an embodiment, the dehydrohalogenation reactions are catalysed. Suchreactions may be carried out in the liquid or vapour phase, preferablythe vapour phase. A temperature of from about −25 to about 700° C. maybe used. Preferred temperatures for the liquid phase are from about 0 toabout 180° C., e.g. from about 15 to about 120° C. Preferredtemperatures for vapour phase dehydrohalogenation are from about 100 toabout 650° C., such as from about 200 to about 600° C., e.g. from about300 to about 500° C.

Catalysed dehydrohalogenation reactions may be carried out atatmospheric, sub- or super-atmospheric pressure, preferably atmosphericor super-atmospheric pressure. For example, the dehydrohalogenation maybe carried out at a pressure of from about 0 to about 40 bara, such asfrom about 1 to about 30 bara, e.g. from about 1 or 5 to about 20 bara.

Preferably, the catalyst is stable in the presence of HF and/or HCl.Suitable catalysts include metal and carbon based catalysts such asthose comprising activated carbon (including acid-washed carbon,activated carbon and three dimensional matrix carbonaceous materials),main group (e.g. alumina-based catalysts) and transition metals, such aschromia-based catalysts (e.g. zinc/chromia) or nickel-based catalysts(e.g. nickel mesh). Examples of such catalysts include alumina,fluorided alumina, aluminum fluoride, aluminum chlorofluoride; metalcompounds supported on alumina, fluorided alumina, aluminum fluoride, oraluminum chlorofluoride; chromium oxide (Cr₂O₃), fluorided chromiumoxide, and cubic chromium trifluoride; oxides, fluorides, andoxyfluorides of magnesium, zinc and mixtures of magnesium and zincand/or aluminum; lanthanum oxide and fluorided lanthanum oxide; carbon,and metal compounds supported on carbon. The metal compounds can beoxides, fluorides, and oxyfluorides of at least one metal selected fromthe group consisting of sodium, potassium, rubidium, cesium, yttrium,lanthanum, cerium, praseodymium, neodymium, samarium, chromium, iron,cobalt, rhodium, nickel, copper, zinc, and mixtures thereof. In someembodiments of this invention, the dehydrohalogenation catalystcomprises alkali metal salt supported on chromium oxide.

The catalyst used may be used in an amount of from about 0.01 to about50% by weight, such as from about 0.1 to about 30%, for example fromabout 0.5 to about 20%, based on the weight of the reagents. The contacttime with the catalyst in the catalysed reaction suitably is from about1 to about 500 seconds, such as from about 5 to about 400 seconds.

The dehydrohalogenation can be carried out in any suitable apparatus,such as a static mixer, a stirred tank reactor or a stirredvapour-liquid disengagement vessel. Preferably, the apparatus is madefrom one or more materials that are resistant to corrosion, e.g.Hastelloy® or Inconel®. The process may be carried out batch-wise or(semi-) continuously, preferably (semi-) continuously.

In an embodiment, the composition comprising the (hydro)halocarbon and acompound of formula R_(f)—C≡CX is prepared by an isomerisation reaction.Suitable reaction conditions and catalysts include those as describedabove in relation to the dehydrohalogenation reactions, optionally atsomewhat lower temperatures. Suitable conditions for isomerisationreactions are described in, for example, WO 2008/125825 and WO2015/059500. By the term ‘isomerisation reaction’, we include structuraland geometric isomerisation, such as structural isomerisation ofCF₂CH═CF₂ (HFO-1234zc) to HFO-1234ze and geometric isomerisation ofZ-HFO-1234ze to E-HFO-1234ze.

In an embodiment, the composition comprising the (hydro)halocarbon and acompound of formula R_(f)—C≡CX is prepared by a fluorination reaction.Suitable reaction conditions and catalysts include those as describedabove in relation to the dehydrohalogenation reactions, but in thepresence of a fluorination agent such as HF. Typically, the HF is usedin a molar excess compared to the starting material, such as from about1:1 to about 70:1, preferably from about 2:1 to about 60:1, such as fromabout 3:1 to about 50:1, for example from about 5:1 to about 40:1.Suitable conditions for fluorination reactions are described in, forexample, EP-A-2154122 and WO 2011/077394.

The (hydro)halocarbon produced in step (i) may be a C₃₋₇(hydro)haloalkene, preferably a hydrohalopropene, such as achlorotrifluoropropene and/or a tetrafluoropropene.

Preferably, the starting material comprises one or more of CCl₃CH₂CCl₂H(HFC-240fa), CF₃CH₂CFClH (HCFC-244fa), CF₃CH₂CF₂H (HFC-245fa), CF₃CF₂CH₃(HFC-245cb), CF₃CFHCFH₂ (HFC-245eb), CF₃CFClCH₃ (HCFC-244bb),HCFO-1233xf, a tetrachloropropene (HCO-1230), Z-HFO-1234ze,Z-HCFO-1233zd, HFO-1234zc and CCl₃CClHCClH₂ (HFC-240db). The startingmaterial may also be CF₃CHClCH₂Cl (HCFC-243db).

Advantageously, the hydrohalopropene is HCFO-1233zd and/or HFO-1234ze,and wherein the starting material comprises one or more of CCl₃CH₂CCO₂H(HFC-240fa), CF₃CH₂CFClH (HCFC-244fa) and CF₃CH₂CF₂H (HFC-245fa), suchas described in, for example, US 2014/228600, which is herebyincorporated by reference. In a further embodiment, the hydrohalopropenecan be E-HCFO-1233zd and wherein the starting material comprisesE-HCFO-1233zd, or the the hydrohalopropene can be E-HFO-1234ze, andwherein the starting material comprises one or more of Z-HFO-1234ze orHFO-1234zc.

Preferably, the hydrohalopropene is HFO-1234yf and the starting materialcomprises one or more of CF₃CF₂CH₃ (HFC-245cb), CF₃CFHCFH₂ (HFC-245eb),CF₃CFClCH₃ (HCFC-244bb), HCFO-1233xf, a tetrachloropropene (HCO-1230)and CCl₃CClHCClH₂ (HFC-240db), such as described in WO 2008/04096 and WO2010/123154, which are hereby incorporated by reference. The startingmaterial for preparing HFP-1234yf may also be CF₃CHClCH₂Cl (HCFC-243db).

Advantageously, the hydrohalopropene is HCFO-1233xf and the startingmaterial comprises a tetrachloropropene (HCO-1230) and/or CCl₃CClHCClH₂(HFC-240db), such as described in WO 2011/077394, which is herebyincorporated by reference.

Preferably, the (hydro)halocarbon is HCFC-244bb and the startingmaterial comprises one or more of HCFO-1233xf, a tetrachloropropene(HCO-1230) and CCl₃CClHCClH₂ (HFC-240db), such as described in WO2007/125199, which is incorporated herein by reference.

In some embodiments of this invention, the composition comprising a(hydro)halocarbon and a compound of R_(f)—C≡CX is mixed with basicsolution comprising an hydroxide, alkoxide and/or amide, optionally inthe presence of a suitable solvent, in a vessel equipped with anagitator. For example, (hydro)halocarbon containing R_(f)—C≡CX impuritymay be contacted with basic solution comprising an hydroxide, alkoxideand/or amide under a suitable amount of pressure to maintain liquidphase of the (hydro)halocarbon and the basic solution comprising anhydroxide, alkoxide and/or amide in a vessel. The contents of thecontacting vessel may be agitated to provide contact between the(hydro)halocarbon and the basic solution comprising an hydroxide,alkoxide and/or amide.

In some embodiments, the contacting step can be carried out bycontacting a gaseous mixture of (hydro)halocarbon and R_(f)—C≡CXimpurity with basic solution comprising an hydroxide, alkoxide and/oramide. For example, the mixture comprising (hydro)halocarbon andR_(f)C≡CX impurity may be bubbled into the basic solution comprising anhydroxide, alkoxide and/or amide as a gas in a stirred vessel. The(hydro)halocarbon is then allowed to leave the contacting vessel,optionally through a condenser, where it can be further purified orrecovered.

In some embodiments, the contacting step is conducted in a column packedwith materials such as helices, rings, saddles, spheres or other formedshapes fabricated from glass, plastic, or ceramics. The mixturecomprising (hydro)halocarbon and R_(f)—C≡CX impurity enters the bottomof the column as a vapour. The basic solution comprising an hydroxide,alkoxide and/or amide enters the top of the column, for example, bymeans of a pump connected to a reservoir of said basic solutioncomprising an hydroxide, alkoxide and/or amide. The R_(f)—C≡CX impurityin the (hydro)halocarbon is then removed by contacting with basicsolution comprising an hydroxide, alkoxide and/or amide in the columnand the (hydro)halocarbon vapour, with reduced R_(f)—C≡CX impurity,passes out the top of the column and is then collected. The basicsolution comprising an hydroxide, alkoxide and/or amide passes out thebottom of the column and returns to the reservoir.

The (hydro)halocarbon is recovered in step (iii) by any suitable meansincluding, for example, distillation and/or phase separation.

The process of the invention may comprise one or more additionalpurification steps, such as distillation, condensation, scrubbing, phaseseparation, acid removal, polishing and/or drying.

HF and optionally HCl may be present in the composition resulting fromthe converting step. Preferably, at least some of the HF, and optionallyHCl, in the composition is removed prior to the contacting step. Theacid can be removed by, for example, by flash separation, aqueousscrubbing and/or distillation. Where bulk removal of HF occurs prior tothe contacting step (ii), residual HF (and optionally HCl) isadvantageously removed by the contacting step.

If the basic solution comprising an hydroxide, alkoxide and/or an amideused in step (ii) is aqueous, it is preferable to have a drying step.Drying of the (hydro)halocarbon can be achieved by known methods, suchas treatment with sulphuric acid and/or contact with a porous medium,such as silica, aluminium-containing adsorbents (e.g. zeolites) oractivated carbon.

As will be understood by the skilled person, any of the preferred andalternative embodiments presented above may be applicable to any of thedescribed aspects of the invention.

The invention is illustrated by the following non-limiting Examples.

EXAMPLES Experimental

A feed mixture was prepared by adding TFMA (2.5 g) to HFO-1234yf (499.98g). This mixture, containing 0.50% wt TFMA, was used for allexperiments.

The solid base was accurately weighed into a 100 ml Hastelloy C22autoclave and dissolved in a known weight of deionised water. If used,the phase transfer catalyst was also added at this point. The vessel wassealed, purged with nitrogen and evacuated. It was then pressurised(4-4.5 Barg) with the HFO-1234yf/TFMA feed mixture. The contents of thevessel were then stirred at 1000 rpm and heated to the desiredtemperature over a period of 4 to 5 minutes. Once at the desiredtemperature, samples of the gas in the headspace of the vessel wereperiodically withdrawn and analysed by gas chromatography.

Results

The experiments were performed using a variety of basic reagents atdifferent concentrations, temperatures and both in the presence andabsence of a phase transfer catalyst (Aliquat 336). The results are setout in Tables 1 to 8.

TABLE 1 (Example 1) Base KOH (85 wt %) 2.1 g Concentration (mol/L) 0.64Temperature (° C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.4633.66 0.37 99.60 71 0.27 99.71 129 0.19 99.81 177 0.13 99.87

TABLE 2 (Example 2) Base KOH (85 wt %) 4.1 g Concentration (mol/L) 1.24Temperature (° C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.4327.5 0.27 99.68 52 0.20 99.78 90 0.13 99.86 193 0.04 99.95

TABLE 3 (Example 3) Base KOH (85 wt %) 2.1 g Concentration (mol/L) 0.64Temperature (° C.) 70 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.48 250.20 99.80 63 0.05 99.95 104 0.02 99.98 130 0.01 99.99

TABLE 4 (Example 4) Base KOH (85 wt %) 4.2 g Concentration (mol/L) 1.27Temperature (° C.) 70 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.49 160.19 99.81 50 0.05 99.95 83 0.02 99.98 118 0.01 99.99

TABLE 5 (Example 5) Base KOH (85 wt %) 4.0 g Concentration (mol/L) 1.21Temperature (° C.) 50 Phase transfer catalyst Aliquat 336 0.1 g Time(mins) TFMA (wt %) 1234yf (%) 0 0.50 99.48 25 0.17 99.83 62 0.05 99.9588 0.02 99.98 124 0.01 99.99

TABLE 6 (Example 6) Base NaOH (85 wt %) 2.1 g Concentration (mol/L) 1.03Temperature (° C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.46 220.43 99.54 74 0.27 99.71 103 0.19 99.80 178 0.10 99.89

TABLE 7 (Example 7) Base NaOH (85 wt %) 4.0 g Concentration (mol/L) 1.97Temperature (° C.) 70 Phase transfer catalyst Aliquat 336 0.1 g Time(mins) TFMA (wt %) 1234yf (%) 0 0.50 99.47 13 0.23 99.75 27 0.07 99.9371 0.01 99.99 130 0.00 100.00

TABLE 8 (Example 8) Base CaO 2.55 g Concentration (mol/L) 0.83Temperature (° C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.54 99.43 390.51 99.46 76 0.50 99.47 130 0.48 99.48 180 0.47 99.50

It can be seen that treatment with a base is very effective in reducingthe absolute concentration of TFMA in the mixture and increasing theHFO-1234yf content of the mixture relative to TFMA overall.

A reduction in other trace impurities was also observed followingtreatment with a base. The results of reducing other impurities aresummarised in Tables 9 and 10.

TABLE 9 (Example 9) Base NaOH (85 wt %) 4.0 g Concentration (mol/L) 1.97Temperature (° C.) 70 Phase transfer catalyst Aliquat 336 0.1 g AreaCounts in Area counts in 1234yf feed 1234yf after Reduction Speciesmaterial treatment (%) Z-1225ye 14.81 3.00 79.8 236ea 2.02 0.00 100.0245eb 21.75 0.00 100.0

TABLE 10 (Example 10) Base KOH (85 wt %) 4.1 g Concentration (mol/L)1.24 Temperature (° C.) 50 Area Counts in Area counts in 1234yf feed1234yf after Reduction Species material treatment (%) 236ea 2.55 0.2789.4 245eb 23.97 0.00 100.0

The process of the invention is therefore also effective in reducing thelevels of R-1225ye(Z), R-236ea and R-245eb in a composition comprisingHFO-1234yf.

Experimental

A feed mixture was prepared by adding TFMA (1.25 g) to an HFO (250 g).These mixtures, containing 0.50% wt TFMA, were used for all experiments.

In a typical scrubbing experiment the base was accurately weighed into a100 ml Hastelloy C22 autoclave and dissolved in a known weight ofdeionised water or solvent. If used, any further additives e.g. KF orcatalysts were also added at this point. The vessel was then sealed,purged with nitrogen, evacuated and heated to the desired temperatureover 5 minutes. Once at temperature the vessel was then pressurised withthe HFO/TFMA feed mixture. The contents of the vessel were then stirredat 1000 pm and samples of the gas in the headspace of the vessel wereperiodically withdrawn and analysed by gas chromatography.

Results

The experiments were performed using a variety of basic reagents andhydrofluoroolefins (HFOs). The results are set out in Tables 11 to 15.

TABLE 11 (Example 11 - TFMA removal from E-1234ze) Base KOH (85 wt %)4.1 g Concentration (mol/l) 1.24 Temperature (° C.) 50 Time (mins) TFMA(wt %) E-1234ze (%) 0 0.50 99.2 1 0.46 99.2 9.5 0.45 99.0 37 0.35 98.962 0.29 99.0 91 0.21 99.2

TABLE 12 (Example 12 - TFMA removal from 1233xf*) Base KOH (85 wt %) 4.1g Concentration (mol/l) 1.24 Temperature (° C.) 50 Time (mins) TFMA (wt%) E-1233xf (%) 0 0.50 98.79 60 0.16 99.29

TABLE 13 (Example 13 - TFMA removal from 1234yf with Sodium Ethoxide inEthanol) Base solution 20 g 21% NaOEt/Ethanol + 40 g Ethanol Temperature(° C.) 50 Time (mins) TFMA (%) E-1234yf (%) 0 0.50 98.96 10 0.10 99.7330 0.03 99.89 56 0.01 99.95

TABLE 14 (Example 14 - TFMA removal from E- 1234yf in the presence offluoride) Base KOH (85 wt %) 5.1 g + 0.06 g KF Base concentration(mol/l) 1.51 Temperature (° C.) 60 Time (mins) TFMA (wt %) E-1234yf (%)0 0.50 98.96 60 0.17 99.63

TABLE 15 (Example 15 - TFMA removal from E- 1234yf in the absence offluoride) Base KOH (85 wt %) 5.1 g Base concentration (mol/l) 1.51Temperature (° C.) 60 Time (mins) TFMA (wt %) E-1234yf (%) 0 0.50 98.9660 0.17 99.59

It can be seen that treatment with a base is very effective in reducingthe absolute concentration of TFMA in its mixture with a range of HFOs,and increasing the HFO content of the mixture relative to TFMA overall.

The invention is defined by the claims.

1. A process comprising contacting a composition comprising a(hydro)halocarbon and a compound of formula R_(f)—C≡CX with a basicsolution comprising an hydroxide, alkoxide and/or an amide to reduce theconcentration of R_(f)—C≡CX, wherein R_(f) is a perfluorinated alkylgroup and X is H, F, Cl, Br, or I.
 2. A process according to claim 1,wherein the compound of formula R_(f)—C≡CX is 3,3,3-trifluoropropyne(trifluoromethylacetylene, TFMA).
 3. A process according to claim 1,wherein the solution is an aqueous solution.
 4. A process according toclaim 1, wherein the solution comprises one or more of an alkali metalhydroxide, alkoxide or amide, an alkaline earth metal hydroxide oramide, or NR₄OH, wherein R is, independently, H, C₁₋₁₀ alkyl, aryl (e.g.phenyl, naphthyl or pyridinyl) or arylalkyl group (e.g. benzyl or C₁₋₁₀alkyl-substituted phenyl).
 5. A process according claim 1, wherein thesolution contains one or more of potassium hydroxide (KOH), sodiumhydroxide (NaOH) or calcium hydroxide (Ca(OH)₂).
 6. A process accordingto claim 1, wherein the solution has a concentration of from about 0.1to about 10 M, preferably from about 0.2 to about 5 M, such as fromabout 0.5 to about 3 M.
 7. A process according to claim 1, wherein the(hydro)halocarbon is a C₃₋₇ (hydro)haloalkene, preferably ahydrohalopropene.
 8. A process according to claim 7, wherein thehydrohalopropene is a chlorotrifluoropropene and/or atetrafluoropropene.
 9. A process according to claim 8, wherein thechlorotrifluoropropene is CF₃CH═CHCl (HCFO-1233zd) and/or CF₃CCl═CH₂(HCFO-1233xf).
 10. A process according to claim 8, wherein thetetrafluoropropene is CF₃CH═CHF (HFO-1234ze) and/or CF₃CF═CH₂(HFO-1234yf).
 11. A process according to claim 1 carried out in thepresence of a phase transfer catalyst.
 12. A process according to claim1 carried out at a temperature of from about 0 to about 100° C.,preferably from about 10 to about 80° C., such as from about 20 to about60° C.
 13. A process according to claim 1 having a contact time betweenthe composition and the solution of from about 1 second to about 4hours, preferably from about 10 seconds to about 3 hours, such as fromabout 1 minute to about 180 minutes.
 14. A process according to claim 1wherein the composition is in the gas phase as least prior to contactingthe solution.
 15. A process according to claim 1 wherein thecomposition, prior to the contacting step, comprises at least about 90%by weight of the (hydro)halocarbon, preferably at least about 95% byweight.
 16. A process according to claim 1 wherein the composition,prior to the contacting step, contains about 10000 ppm or less,preferably about 5000 ppm or less, such as about 1000 ppm or less, ofthe compound of formula R_(f)—C≡CX.
 17. A process according to claim 1wherein the amount of the compound of formula R_(f)—C≡CX in thecomposition is reduced by at least about 50% by weight, preferably atleast about 70% by weight, such as at least about 90% by weight.
 18. Aprocess according to claim 1 wherein following the contacting step, theresulting composition contains from 0 to about 500 ppm, preferably from0 to about 100 ppm, such from 0 to about 10 ppm, of the compound offormula R_(f)—C≡CX.
 19. A process according to claim 1 wherein thecomposition comprising a (hydro)halocarbon and a compound of formulaR_(f)—C≡CX further comprises an undesired (hydro)halocarbon, and whereincontacting the composition with the basic solution comprising anhydroxide, an alkoxide and/or an amide reduces the concentration of theundesired (hydro)halocarbon.
 20. A process according to claim 19 whereinthe undesired (hydro)halocarbon is selected from pentafluoropropenes,pentafluoropropanes, chlorotetrafluoropropanes, hexafluoropropanes andmixtures thereof.
 21. A process according to claim 20 wherein theundesired (hydro)halocarbon is one or more of CF₃CFH═CFH (HFO-1225ye),HFC-245eb, HFC-245fa, HFC-245cb, HCFC-244bb and HFC-236ea.
 22. A processaccording to claim 19 wherein the amount of the undesired(hydro)halocarbon in the composition is reduced by at least about 50% byweight, preferably at least about 70% by weight, such as at least about90% by weight.
 23. A process according to claim 19 wherein following thecontacting step, the resulting composition contains from 0 to about 500ppm, preferably from 0 to about 100 ppm, such from 0 to about 10 ppm, ofthe compound of the undesired (hydro)halocarbon.
 24. A process accordingto claim 1 wherein the composition is a product stream from a processfor producing the (hydro)halocarbon.
 25. A process according to claim 24combined with one or more additional purification steps.
 26. A processfor preparing a (hydro)halocarbon comprising: (i) converting a startingmaterial, optionally in the presence of HF and/or a catalyst, to acomposition comprising the (hydro)halocarbon and a compound of formulaR_(f)—C≡CX, wherein R_(f) is a perfluorinated alkyl group and X is H, F,Cl, Br, or I; (ii) contacting the composition with a basic solutioncomprising an hydroxide, alkoxide and/or an amide to reduce theconcentration of the compound of formula R_(f)—C≡CX; and (iii)recovering the (hydro)halocarbon.
 27. A process according to claim 26,wherein the compound of formula R_(f)—C≡CX is 3,3,3-trifluoropropyne(trifluoromethylacetylene, TFMA).
 28. A process according to claim 26,wherein solution is an aqueous solution.
 29. A process according toclaim 26, wherein the solution comprises one or more of an alkali metalhydroxide, alkoxide or amide, an alkaline earth metal hydroxide oramide, or NR₄OH, wherein R is, independently, H, C₁₋₁₀ to alkyl, aryl(e.g. phenyl, naphthyl or pyridinyl) or arylalkyl group (e.g. benzyl orC₁₋₁₀ alkyl-substituted phenyl).
 30. A process according to claim 29,wherein the solution contains one or more of potassium hydroxide (KOH),sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)₂).
 31. A processaccording to claim 26, wherein the solution has a concentration of fromabout 0.1 to about 10 M, preferably from about 0.2 to about 5 M, such asfrom about 0.5 to about 3 M.
 32. A process according to claim 26,wherein the (hydro)halocarbon is a C₃₋₇ (hydro)haloalkene, preferably ahydrohalopropene.
 33. A process according to claim 32, wherein thehydrohalopropene is a chlorotrifluoropropene and/or atetrafluoropropene.
 34. A process according to claim 33 wherein thestarting material comprises one or more of CCl₃CH₂CCl₂H (HFC-240fa),CF₃CH₂CFClH (HCFC-244fa), CF₃CH₂CF₂H (HFC-245fa), CF₃CF₂CH₃ (HFC-245cb),CF₃CFHCFH₂ (HFC-245eb), CF₃CFClCH₃ (ICFC-244bb), CF₃CHClCH₂Cl(HCFC-243db), HCFO-1233xf, a tetrachloropropene (IHCO-1230),Z-HIFO-1234ze, Z-HICFO-1233zd, HFO-1234zc or CCl₃CClHCClH₂ (HFC-240db).35. A process according to claim 33, wherein the hydrohalopropene isHCFO-1233zd and/or HFO-1234ze, and wherein the starting materialcomprises one or more of CCl₃CH₂CCl₂H (HFC-240fa), CF₃CH₂CFClH(HCFC-244fa) or CF₃CH₂CF₂H (HFC-245fa).
 36. A process according to claim33, wherein the hydrohalopropene is HFO-1234yf and the starting materialcomprises one or more of CF₃CF₂CH₃ (HFC-245cb), CF₃CFHCFH₂ (HFC-245eb),CF₃CFClCH₃ (HCFC-244bb), CF₃CHClCH₂Cl (HCFC-243db), HCFO-1233xf, atetrachloropropene (HCO-1230) or CCl₃CClHCClH₂ (HFC-240db).
 37. Aprocess according to claim 33, wherein the hydrohalopropene isHCFO-1233xf and the starting material comprises a tetrachloropropene(HCO-1230) and/or CCl₃CClHCClH₂ (HFC-240db).
 38. A process according toclaim 33, wherein the (hydro)halocarbon is HCFC-244bb and the startingmaterial comprises one or more of HCFO-1233xf, a tetrachloropropene(HCO-1230) or CCl₃CClHCCl₂ (HFC-240db).
 39. A process according to claim26 wherein the contacting step is carried out in the presence of a phasetransfer catalyst.
 40. A process according to claim 26 wherein thecontacting step is carried out at a temperature of from about 0 to about100° C., preferably from about 10 to about 80° C., such as from about 20to about 60° C.
 41. A process according to claim 26 wherein thecontacting step has a contact time between the composition and thesolution of from about 1 second to about 4 hours, preferably from about10 seconds to about 3 hours, such as from about 1 minute to about 180minutes.
 42. A process according to claim 26 wherein the composition isin the gas phase as least prior to contacting the solution.
 43. Aprocess according to claim 26 wherein the composition, prior to thecontacting step, comprises at least about 90% by weight of the(hydro)halocarbon, preferably at least about 95% by weight.
 44. Aprocess according to claim 26 wherein the composition, prior to thecontacting step, contains about 10000 ppm or less, preferably about 5000ppm or less, such as about 1000 ppm or less, of the compound of formulaR_(f)—C≡CX.
 45. A process according to claim 26 wherein the amount ofthe compound of formula R_(f)—C≡CX in the composition is reduced in thecontacting step by at least about 50% by weight, preferably at leastabout 70% by weight, such as at least about 90% by weight.
 46. A processaccording to claim 26 wherein following the contacting step, theresulting composition contains from 0 to about 500 ppm, preferably from0 to about 100 ppm, such from 0 to about 10 ppm, of the compound offormula R_(f)—C≡CX.
 47. A process according to claim 26 furthercomprising one or more additional purification steps.
 48. A processaccording to claim 26 wherein HF is present in the composition resultingfrom the converting step.
 49. A process according to claim 48 wherein atleast some of the HF in the composition is removed prior to thecontacting step.